Memory corruption with multi-threaded process

[karya0]

I noticed a memory corruption related segfault on my laptop (2 cores, 4 threads) that is not too hard to reproduce. It doesn't even involve creating a checkpoint image.

dmtcp_launch ./test/pthread4

Let it run for a while and eventually, you will see a segmentation fault.

To look closely, you can define env var DMTCP_SEGFAULT_HANDLER=1 and instead of creating a core file it will loop inside the segfault handler function.

The next step should be to disable JAlloc by removing #define from jalloc.h. I couldn't use libc malloc on my laptop due to a separate issue involving isspace() (I'll create a separate issue about that).

[gc00]

Wow! That's a really important find. I was hoping that DMTCP was starting to become really solid (at least the core non-plugin part).

Thanks, Kapil.

• Gene

On Mon, Nov 03, 2014 at 10:29:16AM -0800, Kapil Arya wrote:

I noticed a memory corruption related segfault on my laptop (2 cores, 4 threads) that is not too hard to reproduce. It doesn't even involve creating a checkpoint image.

dmtcp_launch ./test/pthread4

Let it run for a while and eventually, you will see a segmentation fault.

To look closely, you can define env var DMTCP_SEGFAULT_HANDLER=1 and instead of creating a core file it will loop inside the segfault handler function.

The next step should be to disable JAlloc by removing #define from jalloc.h. I couldn't use libc malloc on my laptop due to a separate issue involving isspace() (I'll create a separate issue about that).

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Reply to this email directly or view it on GitHub: https://github.com/dmtcp/dmtcp/issues/15

[rohgarg]

Did you notice this on other systems as well? I left it running on dekaksi but couldn't reproduce this issue.

[karya0]

It was a race in Jalloc. Fixed in 2487ccdd68dc5f508635346237a484e300bc7b39.